Internal heating device for air valves

ABSTRACT

An electrical heating device for valves is presented. The device prevents freezing of water vapor normally present in the compressed air used in pneumatic systems, and thereby allows the use of the compressed air machinery under prolonged low temperature conditions. The device consists of an insulated, electrical heating element which is mounted under any conventional pilot valve, abutting the lower surface valve base. A metal mounting plate having a recess for receiving the heating element is affixed to the valve base and holds the element against the base. Insulating material having a central depression is placed in the recess with the material substantially surrounding the element. The insulating material also extends between the base and the plate to channel heat from the element into the base. The element may be coupled to any conventional power source and is designed to heat the entire valve body.

United States Patent 1 1 liengst rt 1 1 May 15, 1973 [54] INTERNAL HEATING DEVICE FOR 3,538,302 11/1970 Volling ..219/201 AIR VALVES FOREIGN PATENTS OR APPLICATIONS [76] Inventor: Clifford M. Lengstorf, Route No. I,

Whit fi h Mont. 59937 753,884 8/1933 France ..219/201 [22] Flled: 1971 Primary Examiner-A. Bartis 211 App], N 113,947 Att0rney- Lefiane & Shur [52] US. Cl. ..2 19/20l,137/341,138/33, [57] ABSTRACT 219/301, 219/531, 219/535 An electrical heating device for valves is presented. [51] Int. Cl ..H05b l/00, F16k 49/00 The device prevents freezing of water vapor normally [58] Field of Search ..219/200, 201, 205, present in the compressed air used in pneumatic 219/208, 311, 301, 535, 526, 536, 296; systems, and thereby allows the use of the compressed 137/341, 625.64; 138/33 air machinery under prolonged low temperature conditions. The device consists of an insulated, electrical References Cited heating element which is mounted under any conven- UNITED STATES PATENTS tional pilot valve, abutting the lower surface valve base. A metal mountmg plate having a recess for 2,418,557 4/1947 Reiser ..219/535 X receiving the heating element is affixed to the valve ,51 7/1961 Co ins t .-l3 base and holds the element against the base. Insulating 3,080,882 3/1963 Baker 137/341 X material having a central depression is placed in the recess with the material substantially surrounding the 2:518:863 8/1950 Camden et a1. ..219 201 element The insulatihg material extends between 1,151,185 8/1915 Jamieson ..219/201 the base and the Plate to Channel heat from the 2,680,449 6/1954 Toulmin ..219/201 X ment into the base. The element may be coupled to 1,988,289 1/1935 Witteman.... ..137/341 X any conventional power source and is designed to heat 3,575,199 Beattie the entire valve 2,445,185 7/1948 Reiser ..219/526 5 Claims, 3 Drawing Figures PATENTED HAY] 51973 INVENTOR CLIFFORD M LENGSTORF ATTORNEYS 1 INTERNAL HEATING DEVICE FOR AIR VALVES This invention relates to an electrical heating device for valves and particularly to a heating device for control valves in pneumatic systems for use during subfreezing operating conditions.

Condensed water vapor in the compressed air in pneumatic systems each year causes many costly problems. One of the most expensive and difficult to remedy occurs when compressed air systems are utilized to operate machinery during sub-freezing temperatures. The water vapor normally present in the pneumatic system condenses, collects in the control valves, and freezes, thereby causing valve blockage. When the control valve is inoperable the machine controlled by the pneumatic system must be stopped, causing expensive delays. These stoppages not only require hours of maintenance to correct, but are expensive from the standpoint of lost operating time and decreased production.

In the lumber industry, for example, nearly all log moving equipment at sawmills is operated by compressed air systems, powered by electricity. Hoists, jacks, and similar machines are operated by a controlled flow of air from a compressor, through a pilot valve. The valve itself is typically a solenoid operated needle valve. When the operator energizes the system an electrical impulse displaces the needle which, in turn, admits compressed air into the desired cylinder.

When air is compressed for use in a pneumatic system the water vapor therein may condense, and when the valve is exposed to sub-freezing temperatures the condensate normally present collects around the needle, small orifices, the spool, and other. moving parts of the valve and freezes. The frozen condensate renders the valve, and the equipment served thereby inoperative. When a valve freezes production must be curtailed while attempts are made to thaw the frozen parts.

Methods proposed to eliminate this problem have generally been unsuccessful or too expensive to be feasible. I

For example, anelectric heating coil, wire, or tape may be wrapped around the valve in a manner similar to that utilized to prevent freezing with exposed water pipes. Unfortunately, although this method is successful with water pipes, it has not proven successful with pneumatic pilotvalves.

In another method, a heating coil surrounds a core, the end of which is threadedly received in the valve support. Electric current heats the core which conducts heat to the valve. This method, and others which rely on heating a spot or portion of a valve body have also not proven successful. These methods do not sufficiently heat the valve, possibly due to radiation losses. While the area immediately adjacent the heated spot remains warm, the remote areas of the valve body do not remain warm enough to prevent freezing or stickmg.

One other popular method for avoiding freezing in pneumatic systems involves the use of a dry gas, Tanne'r gas which is mixed with the air. However, the use of this gas with the air is expensive and even with such a gas, water vapor still creates problems within the system. This type of solution then is economically un desireable, and not totally successful from an operational standpoint.

Priorto this invention the only reliable approach to cold weather operation of logging equipment involved replacement of pneumatic systems with mechanical. The problem of freezing valves has become so acute that many organizations have undergone the expense of converting to mechanical systems in order to insure uninterrupted production.

The device of this invention readily and dependably solves the problem of freezing valves without the expense of using a gas other than air or converting to a mechanical system. It has been discovered that an electric resistance heating element, such as an elongated immersion heater, is effective to heat the entire valve when mounted according to this invention. The heater is mounted contacting the base of the valve body. lt is received within the recess of a generally U-shaped heavy metal plate and surrounded by substantially on all sides except where facing the base of the valve body insulating material. The insulating material also seals the plate to the base of the valve with the valve spool and heater lying generally parallel to one another. This construction channels heat from the heater into the valve body to effectively heat the whole valve, and thereby prevent freezing and condensation in the valve.

Accordingly, it is an object of this invention to provide an inexpensive and efficient method of preventing stoppages of equipment utilizing pneumatic control systems during sub-freezing temperatures.

It is another object to provide a device for heating control valves for pneumatic systems to prevent ice formation in the valve and the associated shut-down of equipment controlled thereby during cold weather conditions.

It is another object to provide an inexpensive and efficient valve heater for pneumatic valves which will function to prevent valve blockage when the valve is operated during freezing conditions.

It is a further object to provide a pilot valve heating device which is adaptable for use with any conventional control valve in a pneumatic system.

It is yet another object to provide an electrical heating device which may be rapidly mounted on the base of a pneumatic control valve to ensure against the formation of ice within the valve when the system is operated at temperatures below the freezing point of water.

It is yet another object to provide a valve heater for a pilot valve in a pneumatic control system which mounts an electrical heating element in abutting relationship with the base of the valve with an insulated metal plate affixed to the base to channel heat from the element into the valve and thereby heat the entire valve to prevent freezing condensation in the moving parts thereof.

These and other objects will become readily apparent with reference to the following drawings and description wherein:

FlG. l is a perspective view of a pneumatic pilot valve having the device of this invention mounted thereon.

FIG. 2 is a side elevation of the valve of FIG. 1 having the device of this invention mounted thereon.

FIG. 3 is a partial sectional view taken along line 3--3 of FIG. 2.

Although the internal heating device of this invention may be utilized with any conventional pneumatic valve it is preferred for use with a solenoid operated pilot valve such as the VALVAIR type manufactured by Bellows-Valvair of Akron, Ohio, and shown generally in FIGS. 1 through 3.

The valve It) utilizes a manually energized solenoid 12 to admit air from a compressor (not shown) to a spool 14 for cycling operation of a machine (not shown) through conduits 16 or to exhaust through conduit 18. conventionally, the valve base 20 is mounted on a support (not shown) by bolts 22 which extend through the mounting flanges 24.

FIGS. 2 and 3 show the device of this invention including the mounting for the preferred heating element 26. Element 26 may be any conventional heater, but a cylindrical electrically insulated resistance heater is preferred such as the model C205 probe, a I20 volt, 100 watt unit manufactured by Chromalox, Inc. of Murfreesboro, Tennessee.

As shown in FIG. 3 element 26 is disposed in longitudinal alignment with spool 14 against the lower surface 28 of valve base 20, between mounting flanges 24.

Element 26 is supported against surface 28 by a mounting plate 30 and insulating material 32. The plate 30 has a flat base 34 and an upwardly extending, U- shaped valve support 36. Flange 35 on base 34 may be used to mount the heated valve unit on a wall or wher ever desired, and for this purpose, may have holes (not shown) to receive bolts. Support 36 surrounds element 26 on three sides and has threaded holes 38 aligned with valve mounting flanges 24 to receive bolts 22 as shown in FIG. 3. receive The interior area of U-shaped support 36 contains any conventional heat-resistant insulating material 32 such as chopped asbestos. Insulating material 32 serves, with plate 30, to channel heat from the element 26 into valve 10, heating the entire length of spool 14 as well as solenoid 12 by conduction.

As shown in FIGS. 1 and 2, insulating material 32 is inserted around the lower surface 42 of the mounting sleeves 44 for conduits 16 and 18, and at the open portion of the U-shaped support 36 between lower surface 28 in valve base 20 to seal the plate 30 to the valve 10.

As also shown in FIGS. 1 and 2 an electrical cord 46 extends from element 26 through the insulating material 32 to plug 48 which may be used to couple element 26 to a power source (not shown). In the preferred embodiment a conventional 120 volt, alternating current source may be used.

It will be obvious to those skilled in the art that more than one cylindrical heating element may be utilized if desired. Whether more than one element is utilized will be governed primarily by the size and type of valve to be heated and the dimensionalconfines of the area surrounded by the U-shaped valve support 36.

Accordingly, this invention comprises an internal, electrical heating device for control valves in pneumatic systems. This invention has proven effective in tests conducted over a 30 day period of operation at a lumber mill. During this period the temperature reached 45 below zero several times, and did not exceed zero day or night. Inspite of these conditions valves heated with the device of this invention continued in normal operation without freezing. During the same periods all methods used at other neighboring mills proved to be ineffective, allowing these values to freeze.

The device of this invention heats a pneumatic pilot valve internally by mounting an electrical heating element against the base of the valve adjacent the spool.

rounds the element on three sides, containing the insulating material and the said element supported thereby. The plate then holds the element in position against the valve. The mounting plate also may have an external flange used to mount the valve and heating element unit on a wall wherever the unit is to be used.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

l. A pneumatic valve for use in pneumatic systems and operable under subfreezing temperature conditions comprising a valve body having a movable valve element for opening and closing said valve and a control device for actuating said movable valve element;

a heating device including a mounting plate having a face adapted to be attached to a surface of said valve body, said mounting plate having a recess in said face, means connecting said plate to said valve body with said face and said surface in opposition one to the other;

at least one electrical resistance heating element disposed in said recess and in contact with said valve body surface for conducting heat to said valve body, said heating element adapted to be coupled to a source of electric energy;

insulating means disposed within said recess lining the walls thereof and surrounding the surface of said heating element remote from said valve body and the sides thereof for directing heat toward said valve body, said plate and said recess being elongated, said valve element comprising a spool, said electrical resistance heating element comprising a cylindrical probe, said probe being disposed longitudinally in said recess and extending parallel to the longitudinal axis of said spool.

2. The device of claim 1 including sealing means on the face of said plate surrounding said recess so that, when said plate is attached to the surface of said valve body, said sealing means seals said plate to said valve, said insulating means and said sealing means comprising an elongated pad of asbestos having a central depression for supporting said heating element in contact against said valve body, the edges of said pad extending outwardly over a portion of the face of said plate to Heat from the element is channelled into the valve through the use of a unique mounting plate sealed to the valve base with insulating material. The plate surform a gasket between said plate and said valve body. 3. A pneumatic valve for use in pneumatic systems and operable under subfreezing temperature conditions comprising a valve body having a movable valve element for opening and closing said valve and a control device for actuating said movable valve element;

a heating device including a mounting plate having a face adapted to be attached to a surface of said valve body, said mounting plate having a recess in said face, means connecting said plate to said valve body with said face and said surface in opposition one to the other; at least one electrical resistance heating element disposed in said recess and in contact with said valve body surface for conducting heat to said valve body, said heating element adapted to be coupled to a source of electric energy;

insulating means disposed within said recess lining the walls thereof and surrounding the surface of said heating element remote from said valve body and the sides thereof for directing heat toward said valve body, said plate being generally elongated and having a generally U-shaped cross-section with said recess being defined between the legs of the U-shaped plate, said heating element being elongated, said valve element comprising a spool extending generally parallel to the longitudinal axis of said recess, at least one mounting flange extending outwardly from said U-shaped plate for mounting said heating device on a support.

4. A pneumatic valve for use in pneumatic systems and operable under subfreezing temperature conditions comprising a valve body having a movable valve element for opening and closing said valve and a control device for actuating said movable valve element;

a heating device including a mounting plate having a face adapted to be attached to a surface of said valve body, said mounting plate having a recess in said face, means connecting said plate to said valve body with said face and said surface in opposition one to the other;

at least one electrical resistance heating element disposed in said recess and in contact with said valve body surface for conducting heat to said valve body, said heating element adapted to be coupled to a source of electric energy;

insulating means disposed within said recess lining the walls thereof and surrounding the surface of said heating element remote from said valve body and the sides thereof for directing heat toward said valve body, said insulating means comprising an elongated pad of asbestos having a central depression for supporting said heating element and upwardly extending sides, the sides adapted to project outwardly beyond at least a portion of said plate face to form a seal between said plate and said valve body.

5. The device of claim 4 including a recess in the surface of said valve body inopposition to the recess in said plate, said heating element and said insulating means being partly disposed in said surface recess. 

1. A pneumatic valve for use in pneumatic systems and operable under subfreezing temperature conditions comprising a valve body having a movable valve element for opening and closing said valve and a control device for actuating said movable valve element; a heating device including a mounting plate having a face adapted to be attached to a surface of said valve body, said mounting plate having a recess in said face, means connecting said plate to said valve body with said face and said surface in opposition one to the other; at least one electrical resistance heating element disposed in said recess and in contact with said valve body surface for conducting heat to said valve body, said heating element adapted to be coupled to a source of electric energy; insulating means disposed within said recess lining the walls thereof and surrounding the surface of said heating element remote from said valve body and the sides thereof for directing heat toward said valve body, said plate and said recess being elongated, said valve element comprising a spool, said electrical resistance heating element comprising a cylindrical probe, said probe being disposed longitudinally in said recess and extending parallel to the longitudinal axis of said spool.
 2. The device of claim 1 including sealing means on the face of said plate surrounding said recess so that, when said plate is attached to the surface of said valve body, said sealing means seals said plate to said valve, said insulating means and said sealing means comprising an elongated pad of asbestos having a central depression for supporting said heating element in contact against said valve body, the edges of said pad extending outwardly over a portion of the face of said plate to form a gasket between said plate and said valve body.
 3. A pneumatic valve for use in pneumatic systems and operable under subfreezing temperature conditions comprising a valve body having a movable valve element for opening and closing said valve and a control device for actuating said movable valve element; a heating device including a mounting plate having a face adapted to be attached to a surface of said valve body, said mounting plate having a recess in said face, means connecting said plate to said valve body with said face and said surface in opposition one to the other; at least one electrical resistance heating element disposed in said recess and in contact with said valve body surface for conducting heat to said valve body, said heating element adapted to be coupled to a source of electric energy; insulating means disposed within said recess lining the walls thereof and surrounding the surface of said heating element remote from said valve body and the sides thereof for directing heat toward said valve body, said plate being generally elongated and having a generally U-shaped cross-section with said recess being defined between the legs of the U-shaped plate, said heating element being elongated, said valve element comprising a spool extending generally parallel to the longitudinal axis of said recess, at least one mounting flange extending ouTwardly from said U-shaped plate for mounting said heating device on a support.
 4. A pneumatic valve for use in pneumatic systems and operable under subfreezing temperature conditions comprising a valve body having a movable valve element for opening and closing said valve and a control device for actuating said movable valve element; a heating device including a mounting plate having a face adapted to be attached to a surface of said valve body, said mounting plate having a recess in said face, means connecting said plate to said valve body with said face and said surface in opposition one to the other; at least one electrical resistance heating element disposed in said recess and in contact with said valve body surface for conducting heat to said valve body, said heating element adapted to be coupled to a source of electric energy; insulating means disposed within said recess lining the walls thereof and surrounding the surface of said heating element remote from said valve body and the sides thereof for directing heat toward said valve body, said insulating means comprising an elongated pad of asbestos having a central depression for supporting said heating element and upwardly extending sides, the sides adapted to project outwardly beyond at least a portion of said plate face to form a seal between said plate and said valve body.
 5. The device of claim 4 including a recess in the surface of said valve body in opposition to the recess in said plate, said heating element and said insulating means being partly disposed in said surface recess. 